Oh my, this is excellent. Having partially recovered after 12 years of 'CFS', I was thinking about the difference between 'tired' and 'having a crash' CFS style. I haven't slept for two days (insomnia seems to be an ongoing CFS issue for me), BUT even then I am NOWHERE near as exhuasted as I used to be after weeks of good rest. Amazing. Today I can go for a walk, even without the sleep and sure I feel dreadful, but I feel like I'm still in my body, I still feel like me.
CFS is so deeply exhausting it takes away one's sense of self. It's like you've turned into a colander and all of your energy has drained away.